Aqueous chemical solutions are used in a variety of situations. For example, in different applications, aqueous cleaning solutions are used to clean, sanitize, and/or disinfect kitchens, bathrooms, schools, hospitals, factories, and other similar facilities. Aqueous cleaning solutions typically include one or more chemical species dissolved in water. The chemical species impart various functional properties to the water such as cleaning properties, antimicrobial activity, and the like. Measuring the concentration of the chemical species in the aqueous solution before use can be beneficial to understand the properties of the solution and to determine if adjustment is required. For example, chemical solution monitoring can be especially useful in many industrial applications. In some cases, substantially real-time monitoring is used to determine a concentration of a chemical in a cleaning solution and then to adjust the chemical concentration during a short period of cleaning. In other cases, measurements may be taken on a periodic basis to maintain a nominal chemical concentration in the solution during a comparatively long period of operation.
An optical sensor is one type of device that can be used to analyze a chemical solution. The optical sensor may direct light through an optical window into a fluid solution and receive light from the fluid through an optical window. The optical sensor may direct and receive light through the same optical window or different optical windows. In either case, the optical sensor may determine a characteristic of the fluid solution based on the light received from the fluid solution. For example, the optical sensor may determine a concentration of a chemical species in the fluid based on the wavelength and/or magnitude of light received from the fluid.
In some applications, an optical sensor may be used to determine a characteristic of a fluid that contains a fouling material. In such a situation, an optical window of the optical sensor may become fouled, restricting the amount of light directed and/or received through the optical window. When light is restricted, the optical sensor may not determine a characteristic of the fluid solution as accurately as when the optical window is comparatively cleaner. For example, the optical sensor may attribute a reduced magnitude of received light from the fluid solution as being indicative of the fluid solution having a lower concentration of a chemical species rather than attribute the reduced amount of light to fouling interference.